Field of the Invention
This invention relates to manufacture of fibers or filaments, and particularly to the manufacture of metal fibers or filaments.
Description of the Prior Art
There has long been a need for low cost metal fibers as substitutes for conventional textile materials and in numerous other applications where the desirable chemical and physical characteristics of such metal fibers provides improved functioning and features heretofore unavailable. Recently, an improved process for forming metal fibers has been developed by the assignee hereof based on the novel concepts of the U.S. Pat. issued Oct. 11, 1966 to Webber et al., No. 3,277,564, for a "Method of Simultaneously Forming a Plurality of Filaments", and Roberts et al., issued July 23, 1968, No. 3,394,213, for a "Method of Forming Filaments", each of these patents being owned by the assignee hereof. The development of such a fiber forming technology has provided a substantially new field of fiber products by reducing the theretofore exorbitant cost of such metal fibers to a reasonable value. Whereas prior to the technology developed by the assignee hereof the cost of such metal fibers was measured in the hundreds of dollars per pound, the cost today has been reduced to a small fraction thereof.
Broadly, the technique so developed by the assignee hereof in economically manufacturing extremely small diameter metal filaments has been to constrict a plurality of originally relatively large metal elements, such as wires or rods, concurrently whereby a multiplicity of constricting operations is effected by a single operation. Thus, as disclosed in the above identified Webber et al., patent, one method of forming such filaments is to sheath a plurality of wires in a suitable sheathing material, bundle a plurality of sheathed wires in a suitable housing, or can, and draw the housed bundle through a plurality of drawing steps to the final desired size. To provide extremely small diameter filaments, a rebundling of the drawn bundles may be effected. Resultingly, the final drawing operation may involve the drawing of a million or more such previously constricted wires. By concurrently drawing such a large number of wires in the final workpiece, substantial economies may be effected in the production of the small diameter filaments.
The above mentioned Roberts et al patent teaches a modification of the Webber et al process in utilizing a hot forming operation prior to the drawing operation thereby providing different metallurgical and operational characteristics. As a concomitant of the improved characteristics obtained, further reduction in the cost of the manufacture of the filaments may be realized by utilization of the relatively low cost hot forming initial steps. Thus, the Roberts et al technology provided further improvement in the reduction of the cost of the fibers as manufactured by the assignee hereof.
The filaments and fibers produced in conformity with the teachings of these patents have been recognized by those skilled in the art as superior filaments. The prior techniques of forming metal fibers, such as steel wool and the like, wherein metal pieces are scraped or otherwise machined from metal blocks or sheets, produces ragged, nonuniform fibers, which are substantially inferior to the controlled geometric fibers obtained by the Webber et al and Roberts et al patent techniques. The prior art techniques, however, have had one advantage in that they produce fibers at relatively low cost.